LTC2484CDD#PBF Linear Technology, LTC2484CDD#PBF Datasheet
LTC2484CDD#PBF
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LTC2484CDD#PBF Summary of contents
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... L, LT, LTC and LTM, Linear Technology and the Linear logo are registered trademarks and No Latency ΔΣ and Easy Drive are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Patents pending. ...
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... LTC2484I ............................................ –40°C to 85°C Storage Temperature Range .................. –65°C to 125°C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LTC2484CDD#PBF LTC2484CDD#TRPBF LTC2484IDD#PBF LTC2484IDD#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. ...
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ELECTRICAL CHARACTERISTICS (2x SPEED) full operating temperature range, otherwise specifi cations are at T PARAMETER CONDITIONS Resolution (No Missing Codes) 0.1 ≤ V Integral Nonlinearity 5V ≤ V 2.7V ≤ V Offset Error 2.5V ≤ V Offset Error Drift 2.5V ...
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LTC2484 ANALOG INPUT AND REFERENCE temperature range, otherwise specifi cations are at T SYMBOL PARAMETER + + C ( Sampling Capacitance S – – Sampling Capacitance Sampling Capacitance S ...
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TIMING CHARACTERISTICS range, otherwise specifi cations are at T SYMBOL PARAMETER f External Oscillator Frequency Range EOSC t External Oscillator High Period HEO t External Oscillator Low Period LEO t Conversion Time for 1x Speed Mode CONV_1 t Conversion Time ...
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LTC2484 TYPICAL PERFORMANCE CHARACTERISTICS Integral Nonlinearity ( 5V) CC REF REF 2.5V IN(CM GND O –45°C 1 25°C 0 85°C –1 –2 –3 ...
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TYPICAL PERFORMANCE CHARACTERISTICS RMS Noise vs Input Differential Voltage 1 REF 0 2.5V IN(CM 25°C A 0.8 0.7 0.6 0.5 0.4 –2.5 –2 –1.5 –1 –0.5 0 0.5 1 ...
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LTC2484 TYPICAL PERFORMANCE CHARACTERISTICS Temperature Sensor vs Temperature 0. 1.4V REF f = GND O 0.35 0.30 0.25 0.20 –60 – 120 TEMPERATURE (°C) 2484 G19 On-Chip Oscillator Frequency vs ...
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TYPICAL PERFORMANCE CHARACTERISTICS Conversion Current vs Output Data Rate 500 REF GND 450 – GND SCK = NC 400 SDO = SDI = GND 350 CS ...
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LTC2484 TYPICAL PERFORMANCE CHARACTERISTICS Offset Error (2x Speed Mode) 250 V = 2.5V REF GND IN(CM) 200 f = GND 25°C A 150 100 ...
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PIN FUNCTIONS 0.5 • Outside this input range the converter produces REF unique overrange and underrange output codes. CS (Pin 6): Active LOW Chip Select. A LOW on this pin enables the digital input/output and wakes up the ...
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LTC2484 TEST CIRCUITS SDO 1.69k C Hi Hi-Z OH TIMING DIAGRAMS SDO t 3 SCK SDI SLEEP SDO t 5 SCK SDI SLEEP 12 ...
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APPLICATIONS INFORMATION CONVERTER OPERATION Converter Operation Cycle The LTC2484 is a low power, delta-sigma analog-to-digital converter with an easy to use 4-wire serial interface and automatic differential input current cancellation. Its operation is made up of three states. The converter ...
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LTC2484 APPLICATIONS INFORMATION Through timing control of the CS and SCK pins, the LTC2484 offers several fl exible modes of operation (internal or external SCK and free-running conversion modes). These various modes do not require programming confi guration registers; moreover, ...
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APPLICATIONS INFORMATION Several applications leveraging this feature are presented in more detail in the applications section. While operating in this mode, the speed is set to normal independent of control bit SPD. Rejection Mode (FA, FB) The LTC2484 includes a ...
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LTC2484 APPLICATIONS INFORMATION indicating the initiation of a new conversion cycle. This bit serves as EOC (bit 31) for the next conversion cycle. Table 3 summarizes the output data format. As long as the voltage on the IN+ and IN– ...
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APPLICATIONS INFORMATION –80 –85 –90 –95 –100 –105 –110 –115 –120 –125 –130 –135 –140 –12 –8 – DIFFERENTIAL INPUT SIGNAL FREQUENCY DEVIATION FROM NOTCH FREQUENCY f Figure 3. LTC2484 Nomal Mode Rejection When Using an External Oscillator ...
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LTC2484 APPLICATIONS INFORMATION fi rst conversion result following POR is accurate within the specifi cations of the device if the power supply volt- age is restored within the operating range (2.7V to 5.5V) before the end of the POR time ...
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APPLICATIONS INFORMATION + – – from –FS to +FS where FS = 0.5 • Outside this range, the converter indicates the overrange or the underrange condition using distinct output codes. Since the differential ...
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LTC2484 APPLICATIONS INFORMATION TEST EOC (OPTIONAL) CS TEST EOC BIT 31 BIT 30 EOC SDO Hi-Z Hi-Z SCK (EXTERNAL) SDI DON’T CARE EN CONVERSION SLEEP SLEEP Figure 5. External Serial Clock, Single Cycle Operation TEST EOC (OPTIONAL) CS TEST EOC ...
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APPLICATIONS INFORMATION At the conclusion of the data cycle, CS may remain LOW and EOC monitored as an end-of-conversion interrupt. Alternatively, CS may be driven HIGH setting SDO to Hi-Z. As described above, CS may be pulled LOW at any ...
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LTC2484 APPLICATIONS INFORMATION Internal Serial Clock, Single Cycle Operation This timing mode uses an internal serial clock to shift out the conversion result and a CS signal to monitor and control the state of the conversion cycle (see Figure 8). ...
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APPLICATIONS INFORMATION TEST EOC <t EOCtest CS BIT 31 BIT 30 EOC SDO Hi-Z Hi-Z SCK (INTERNAL) SDI DON’T CARE EN CONVERSION SLEEP SLEEP TEST EOC (OPTIONAL) >t EOCtest CS TEST EOC BIT 0 EOC SDO Hi-Z Hi-Z Hi-Z Hi-Z ...
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LTC2484 APPLICATIONS INFORMATION Internal Serial Clock, 3-Wire I/O, Continuous Conversion This timing mode uses a 3-wire interface. The conversion result is shifted out of the device by an internally gener- ated serial clock (SCK) signal, see Figure 10. CS may ...
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APPLICATIONS INFORMATION Preserving the Converter Accuracy The LTC2484 is designed to reduce as much as possible the conversion result sensitivity to device decoupling, PCB layout, antialiasing circuits, line frequency perturbations and so on. Nevertheless, in order to preserve the 24-bit ...
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LTC2484 APPLICATIONS INFORMATION Driving the Input and Reference The input and reference pins of the LTC2484 converter are directly connected to a network of sampling capaci- tors. Depending upon the relation between the differential input voltage and the differential reference ...
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APPLICATIONS INFORMATION rithm that forces the average differential input current to zero independent of external settling errors. This allows accurate direct digitization of high impedance sensors without the need for buffers. Additional errors resulting from mismatched leakage currents must also ...
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LTC2484 APPLICATIONS INFORMATION Reference Current In a similar fashion, the LTC2484 samples the differential + reference pins V and GND transferring small amount REF of charge to and from the external driving circuits thus producing a dynamic reference current. This ...
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APPLICATIONS INFORMATION –6 in 1.67 • 10 • f ppm gain error. The typical +FS and EOSC –FS errors for various combinations of source resistance seen by the V pin and external capacitance connected REF to that pin are shown ...
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LTC2484 APPLICATIONS INFORMATION V translates into about 2.18 • 10 REF tional INL error. Figure 19 shows the typical INL error due to the source resistance driving the V C values are used. The user is advised to minimize the ...
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APPLICATIONS INFORMATION through the input and the reference pins. If large external input and/or reference capacitors (C previous section provides formulae for evaluating the effect of the source resistance upon the converter performance for any value ...
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LTC2484 APPLICATIONS INFORMATION second, the user is advised to maximize the power supply voltage used and to limit the maximum ambient operating temperature. In certain circumstances, a reduction of the differential reference voltage may be benefi cial. Input Bandwidth The ...
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APPLICATIONS INFORMATION at the 3dB frequency. When the internal oscillator is used, the shape of the LTC2484 input bandwidth is shown in Figure 28. When an external oscillator of frequency f is used, the shape of the LTC2484 input bandwidth ...
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LTC2484 APPLICATIONS INFORMATION Normal Mode Rejection and Antialiasing One of the advantages delta-sigma ADCs offer over conventional ADCs is on-chip digital fi ltering. Combined with a large oversampling ratio, the LTC2484 signifi cantly simplifi es antialiasing fi lter requirements. Additionally, ...
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APPLICATIONS INFORMATION 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 INPUT SIGNAL FREQUENCY (Hz) Figure 32. Input Normal Mode Rejection MEASURED DATA ...
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LTC2484 APPLICATIONS INFORMATION be considered (see Input Current section). In this case, the differential input current cancellation feature of the LTC2484 allows external RC networks without signifi cant degradation in DC performance. Traditional high order delta-sigma modulators, while providing very ...
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APPLICATIONS INFORMATION Using the 2x speed mode of the LTC2484, the device bypasses the digital offset calibration operation to double the output data rate. The superior normal mode rejection is maintained as shown in Figures 30 and 31. However, the ...
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LTC2484 APPLICATIONS INFORMATION Complete Thermocouple Measurement System with Cold Junction Compensation The LTC2484 is ideal for direct digitization of thermocouples and other low voltage output sensors. The input has a typical offset error of 500nV (2.5μV max) offset drift of ...
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APPLICATIONS INFORMATION /*** read _ LTC2484() ************************************************************ This is the function that actually does all the work of talking to the LTC2484. The spi _ read() function performs an 8 bit bidirectional transfer on the SPI bus. Data changes state ...
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LTC2484 PACKAGE DESCRIPTION 3.50 0.05 1.65 0.05 2.15 0.05 (2 SIDES) 0.25 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (SEE NOTE 5) 0.200 REF 40 DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG ...
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... Conditions in Digital Inputs and Digital Outputs section IH Added Note 16 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC2484 PAGE NUMBER ...
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... BAT54 RB6 10k RB5 MCLR 25 RB4 24 RB3 23 RB2 22 RB1 21 RB0 7 RA5 6 RA4 5 RA3 4 RA2 9 3 RA1 RA0 V SS 2484 F44 Noise P-P Noise, 2ppm INL Noise, 4ppm INL, Noise RMS LT 0610 REV C • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2005 2484fc ...